In 2016, NASA's Mars rover Curiosity will get a companion – a new lander that aims to help scientists figure out how the planet formed and evolved, from core to crust.

In doing so, the project could shed additional light on how a planet that could have been hospitable to life early in its history became so hostile to it today, at least on the surface.

NASA officials announced the mission during a briefing late Monday afternoon. Known as InSight, the lander aims to use a seismometer to determine the size, makeup, and current condition of the planet's core, develop a profile of the planet's crust, analyze its mantle, measure the planet's marsquake activity, and measure the rate at which meteors are striking the planet's surface. In addition, the lander will sink a probe several meters into the soil to help estimate how the planet's temperature varies with depth.

As for habitability, on a planetary scale what goes on under the crust can be just as important as what goes on at the surface, astrobiologists note.

Global magnetic fields – which Mars no longer has – can deflect cosmic rays and charged particles from solar storms, which can threaten organisms on the surface. Earth's magnetic field results from the motions of an electrically conductive molten-iron outer core. On Mars, this dynamo has shut down.

On Earth, heat from the core also drives plate tectonics – a planetary heat-exchanger in which the crust is constantly recycled between taffy-like material in the mantle and solid surface. Tectonics triggers volcanism, whose gases can play an enormous role in readjusting the composition of a planet's atmosphere – including the amount of water vapor – and hence its climate.